the 435B never had a torque converter but a two stage cent clutch reduction...
it's a one wheel drive and TCs on one wheel drives are only a mediocre idea..
Also: the original reduction is 10.5:1
sprockets : 10->35-9->27 (35/10 * 27/9)
or on 2004 models (older) 7.9:1
sprockets : 10->35-12->27
(which had some issues and was fixed 2005 as above)
you could've just bought a new jackshaft
https://www.mfgsupply.com/gomini/go...ckshaftonly/az8180-10-threaded-jackshaft.html
or
https://www.gokartsupply.com/jackshft.htm
or best:
https://www.bmikarts.com/Custom-Jackshaft-58-or-34_p_30265.html
give them a call and order 10.375" long 5/8"OD threaded ends
that'd be the best idea (and offer the cheapest fix)
Anyhow.. you cannot just install a Torque converter, with that tiny 27T axle sprocket that kart will not move
you only get a 2.7:1 chain ratio...
and even if the TaVkit you got is stuck in lowest gear at all times, it can only add 2.7:1 ratio itself
and you end up with an overall raio of only 7.3:1
(that and the ~25% power loss in the TC itself will render your kart stationary)
Soooo.. two choices:
a) buy a jackshaft and fix what was there (max 35 bucks)
and return the Tavkit for a full refund since you were given VERY bad advise
or
b) get a different axle sprocket with roundabout 45T instead (minimum 38)
and a new brake system (30 sprocket, 50 brake.. and whatever you paid for the Tavkit)
'sid